 Surtseyan eruptions are the "wet" equivalent of ground-based Strombolian eruptions, but because of where they are taking place they are much more explosive.This is because as water is heated by lava, it flashes in steam and expands violently, fragmenting the magma it is in contact with into fine-grained ash.Surtseyan eruptions are the hallmark of shallow-water volcanic oceanic islands, however they are not specifically confined to them.